The 2005/2006 Ford GT was designed to outperform the Ferrari 360 Modena, the current Ferrari street car at the time, and to represent and showcase the engineering capability of the Ford Motor Company, thus being titled as "The Pace Car for an Entire Company." To this end, they emulated the body lines of the Ford GT40 of the 1960s, one of the greatest racing cars Ford had ever built, and which was known and respected worldwide.
It was NOT designed toward any homologation rules of any racing formula in effect at that time, but rather was designed to meet the 50 state vehicle regulations of the United States (& Canada), including all safety and emission compliancy. Even the Ford Racing Power Upgrade package (P/N M-2005-GT) was not released until it was approved by the EPA for compliancy to emission regulations.
The resulting design, the Ford GT which most us are proud to own, not only achieved it's goal (against the 360), but in fact outperformed the Ferrari 430, the street successor to the 360.